Wear assemblies are widely known in different types of industrial machinery or equipment such as, for example, excavating machinery, e.g. excavators, bulldozers, angle-dozers, mechanical shovels, shovel loaders, road rollers, tamping machines, dragline buckets, etc, and in general earth-moving equipment and material displacement machinery having parts subjected to wear.
It is known in the art to provide such industrial machinery or equipment with wear elements, also referred to as fingers, tips or tooth points. The wear elements are mechanically configured to engage and displace materials such as earth. In use, the wear elements are attached the machinery through a support element, also referred to as adapter. The support element or adapter can be engaged to or be part of the machinery itself.
Mutual attachment of wear elements and support elements in machinery is commonly carried out through corresponding retaining pins. The wear elements and the support elements attached through corresponding retaining pins form the respective wear assemblies.
The parts of the wear assembly, especially the wear elements, operate in harsh working conditions and they are subjected to very heavy loading and a high degree of wearing in use. The purpose of the wear elements is typically to protect the support element or parts of the machinery from premature wear. The wear elements wear out frequently and require periodic replacement. Therefore a quick and easy removal is required while ensuring that the wear elements and the support elements are securely mounted in order to withstand the considerable forces exerted on both elements during operation.
The configuration of retaining pin as well as the portion of the wear element and the support element where the retaining pin is received is of great importance. For attaching the wear elements to the corresponding support elements, the retaining pins are typically forcibly driven into aligned portions of the wear element and the support element. This is carried out by hitting a tool such as a sledge hammer or the like until the retaining pin has been properly inserted into the wear element and the support element. Detaching the wear element from the support element requires the corresponding retaining pin to be forcibly pounded out. This can give rise to a safety hazard for the operator in installing and removing operations. In addition, in such installing and removing operations the retaining pin may become deformed, so its extraction may become a difficult operation.
Document WO2011125794 discloses a retaining pin for attaching a wear element to a support element. Bushings, bolts, and washers are provided to prevent the retaining pin from falling off the wear element and the support element.
Document U.S. Pat. No. 4,918,843 also discloses a retainer pin assembly for attaching a wear element to a support element. The retainer pin assembly has a spring retainer, a retainer pin, and a holder.
Both solutions suffer from the disadvantage that several parts are necessary in combination with the retaining pin for attaching the wear element to the support element involving undesirably complexity and high costs.
Document WO2005095720 also discloses a retaining pin for attaching two mechanical parts to one another in a detachable manner. The retaining pin and the mechanical parts to be attached to each other are configured such that as the retaining pin is rotated it becomes locked (or unlocked). This is carried out by the provision of two or more inclined surfaces in conjunction with elastically loaded tension elements projecting in the axial direction of the pin.
Document U.S. Pat. No. 5,983,534 provides a lock structure for attaching a wear element to a support element. When the support element is received into the lock structure it can be axially inserted therein in a first rotational orientation and then forcibly rotated to a second rotational orientation. The wear and support elements have openings which surfaces are configured to radially inwardly displace a force exerting member in response to such rotation causing a continuous resilient force to be exerted to the elements tending to tighten them to each other. As the lock structure is rotated during its installation, a ramped surface on the support element permits it to snap into a retaining pocket thereon preventing further rotation of the lock structure.
These above solutions have the disadvantage that the provision of parts having inclined planes or surfaces configured in correspondence with tension elements renders the arrangement complex and therefore the whole assembly capital intensive.
A need still exists for an improved wear assembly in which parts involved therein can be easily, quickly and safely attached and detached, for example in maintenance and/or repair operations.